It is a well understood principle that as a right becomes more difficult to (lawfully) exercise, fewer people will (lawfully)exercise that right. This holds true for guns, and many of the so-called “reasonable restrictions” on guns actually amount to de facto gun bans:
The National Firearms Act (26 U.S.C. § 53)
This act of the US Congress banned machine guns, short barreled rifles and shotguns, grenades, sound suppressors, and a variety of related items (more information here). This ban was accomplished not by an outright prohibition against possession of these items, but by requiring that a person who wanted to own such an item obtain permission from the ATF, obtain a signature from local law enforcement, pass a rigorous background check, submit a photograph, submit fingerprints, register the firearm, receive ATF written permission before moving the firearm across state lines, and pay a substantial tax. Later, the registration of machine guns produced after 1989 was also banned banned by 18 U.S.C. § 921, which means the number of lawful machine guns falls each year, pushing the price of a machine gun higher and higher. Today, about 1/2 of the individual states have their own outright bans on machine guns. The result: a dramatic decrease in the manufacture, sale, and ownership of the regulated items, along with a corresponding increase in price, to the point that most people today have never seen a (lawfully) owned machine gun. I’m not criticizing the decision to ban some of those items, such as grenades, however I think the ban on sound suppressors was misguided. More importantly, it is clear that a law that proports to “regulate” is really a ban.
The District of Columbia “emergency ” gun laws
Right after the Supreme Court struck down the unconstitutional handgun ban in Washington, D.C., the city passed a new gun law that required gun owners to take a written exam, provide proof of residency, provide proof of good vision, pay a registration fee, be fingerprinted, pass (another) criminal background check, etc. The result was that very few residents of D.C. chose to register their guns – in fact, only one person tried to register on the first day. In effect, this “regulation” was another ban to be challenged in court.
Other proposed “regulations” that are de facto bans
In Illinois, there have been suggestions that the cost of a Firearms Owner ID Card (FOID) be raised to $500 per year or $500 for 5 years, which would prevent many people from being able to afford to own a gun. Some some have suggested a 500% increase on the tax applied to firearms and ammunition, that would also price many law abiding people out of the market. Others favor bans on so-called “junk guns“, which would deny poorer people the ability to buy a gun for self defense. In each case, the “regulation” is really just a way to erode gun ownership to some degree, and it is hard to quantify what is a “regulation” versus what is a “ban”.